JP4419581B2 - Image forming apparatus and printing result inspection apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including an inspection unit that inspects an image printing result by a printing unit, a printing result inspection apparatus that inspects an image printing result by the image forming apparatus, and a method thereof.

  Conventionally, an image forming apparatus including an inspection unit is known. The inspection unit reads an image printed on a sheet with a reading device, and determines whether the print result is good or not based on inspection image data that is an obtained image. According to the image forming apparatus provided with such an inspection unit, it is possible to automatically determine whether the printing result is good or not, and to take a countermeasure such as reprinting if the printing is defective. As a result, more reliable image printing is possible. Here, since the quality determination of the print result is performed based on the inspection image data read by the reading device, the inspection cannot be accurately performed unless the inspection image data can be acquired accurately.

  By the way, the printed paper may be curled or swelled in advance or during the printing process. Even if the paper curls or swells, if the image is printed normally, the print result is normal.

Japanese Patent Laid-Open No. 11-271951

  However, when the paper is curled or undulated, the inspection image data cannot be obtained accurately. That is, when the paper is curled or undulated, the image printed on the paper also appears distorted, and an accurate inspection image cannot be read by the image reading apparatus.

  Therefore, conventionally, a method for keeping the conveyed paper in a flat shape has been proposed. For example, Patent Document 1 discloses an image formation including an elastic member that keeps an image recording material in a flat shape by slidingly contacting an image recording material that moves on a conveyance guide plate that forms a conveyance path against a conveyance guide plate surface. An apparatus is disclosed. This elastic member is called mylar in which an elastic material is formed in a thin plate shape. With this elastic member, the paper can be flattened by correcting the curl and undulation generated on the paper by pressing the paper.

  However, the conventional image forming apparatus does not consider the positional relationship between the image reading apparatus and the elastic member for keeping the sheet flat. Therefore, there are cases where accurate inspection image data cannot be obtained depending on the arrangement position. In that case, it is impossible to inspect the printing result with high accuracy.

  Therefore, an object of the present invention is to provide an image forming apparatus, a printing result inspection apparatus, and a method thereof that can inspect a printing result with higher accuracy.

An image forming apparatus of the present invention is an image forming apparatus that includes a printing unit that prints an image on a sheet based on document image data, and an inspection unit that inspects an image printing result by the printing unit. A reading unit that is provided on the paper conveyance path formed by the conveyance guide plate and that reads the image printed on the paper by the printing unit to obtain the inspection image data, and determines whether the print result is good or bad based on the inspection image data. And a pressing unit that presses the sheet against the conveyance guide plate in the vicinity of the image reading position by the reading unit to flatten the sheet, and the pressing unit has a tip immediately before the image reading position. A main sheet which is a flexible sheet-like member suspended on the conveyance guide plate so as to be sandwiched between the conveyance guide plate and the main sheet. And Adjusting the pressing force to press the paper against the conveyance guide plate by adjusting the adjustment sheet consisting of a flexible sheet-like member and the adjustment sheet by moving the adjustment sheet in the conveyance direction And a conveying direction moving means.

  In another preferred aspect, the pressing unit further includes a sub-sheet that is a flexible sheet-like member that is hung on the conveyance guide plate at a position immediately after the image reading position. In another preferred aspect, the judging means judges the quality of the print result by comparing and comparing the inspection image data and the document image data.

A printing result inspection method disclosed in the present specification is a printing result inspection method for inspecting an image printing result by an image forming apparatus that prints an image on a sheet based on original image data, and is a sheet formed by a conveyance guide plate A reading process for reading the image printed on the paper by the image forming apparatus and acquiring the inspection image data, and a determination process for determining whether the printing result is good or not based on the inspection image data. , reading of the image in the read process, the paper in front of the image reading position, the front end is a sheet-like member having a flexible that hung down the conveyance guide plate so that just before the image reading position mainly The sheet is pressed against the conveyance guide plate by a sheet, and the sheet is flattened. When the sheet is pushed up to the conveyance guide plate, a flexible sheet-like member suspended on the main sheet is used. That the adjustment sheet, is moved in the conveying direction, to adjust the force of pressing the by adjusting the sag position of the adjustment sheet, it is characterized.

Another printing result inspection apparatus according to the present invention is a printing result inspection apparatus that is attached to an image forming apparatus that prints an image on a sheet based on original image data and inspects an image printing result by the image forming apparatus, A reading unit that is mounted on the conveyance path of the image forming apparatus formed by the guide plate and reads the image printed on the sheet by the image forming apparatus to acquire the inspection image data, and the quality of the print result based on the inspection image data Determining means for determining, and pressing means for pressing the paper against the conveyance guide plate in the vicinity of the image reading position by the reading means to flatten the paper, and the front end of the pressing means is the image reading position. a main sheet is a sheet-like member having a flexible which hung down on the transport guide plate so that just prior to a main sheet sandwiching the sheet conveyed by the conveyance guide plate The adjustment sheet is made of a flexible sheet-like member that is hung on the main sheet, and the adjustment sheet is moved in the conveyance direction to adjust the position of the adjustment sheet. Transport direction moving means for adjusting a pressing force pressed against the guide plate.

  Here, the image forming apparatus refers to all apparatuses having a function of printing an image, such as a printer, a copier, a facsimile, and a digital multi-function peripheral that combines these. In addition to normal printing paper, paper refers to all sheet-like printing media such as postcards, cardboard, cloth, and OHP sheets.

  According to the present invention, since the sheet can be flattened in the vicinity of the image reading position, accurate inspection image data can be obtained. Therefore, it is possible to inspect the printing result with higher accuracy.

  Hereinafter, a printer 10 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overall configuration diagram of the printer 10. 2 is a schematic side view of the vicinity of the inspection device 16 in the printer 10, and FIG. 3 is a schematic top view thereof. The printer 10 described below is assumed to be a relatively large high-speed printer. However, it may be applied to other image forming apparatuses such as a copying machine and a small printer by appropriately changing a part of the configuration.

  The printer 10 is controlled by an image printing control unit (not shown), and forms the same image as the original image stored in the image printing control unit on a sheet. The paper stored in the storage unit 22 is transported along the main transport path 14 and an image is printed in the printing unit 12. The print result is inspected by an inspection device 16 provided downstream of the printing unit 12. Then, according to the inspection result, the sheet is conveyed to the paper discharge unit 24 or the duplex conveyance path 18. Hereinafter, the printer 10 will be described in detail.

  The conveyance path on which the sheet is conveyed is roughly divided into a main conveyance path 14, a duplex conveyance path 18, and a discharge conveyance path 21. The main conveyance path 14 is a conveyance path that guides the sheet from the storage unit 22 to the transfer unit 26 and the inspection device 16. The double-sided conveyance path 18 is a conveyance path branched downstream of the main conveyance path 14, and is a conveyance path that turns the paper over and guides it to the main conveyance path 14 again. The paper discharge transport path 21 is a transport path that branches from the main transport path 14 and guides printed paper to the paper discharge unit. Each of the transport paths 14, 18, and 21 is formed by a transport guide plate 38 that guides the movement of the paper. A transport roller 15 is provided at a predetermined position of the transport guide plate 38, and the paper is transported along the transport guide plate 38 by driving the transport roller 15.

  The storage unit 22 includes two first paper supply trays 30 having a relatively small capacity and two second paper supply trays 32 having a relatively large capacity as paper supply trays for storing paper. Each of the trays 30 and 32 is connected to the main transport path 14 so that paper can be appropriately supplied to the main transport path 14.

  The printing unit 12 is roughly divided into a transfer unit 26 that forms a toner image based on document image data and transfers the toner image onto a sheet, and a fixing unit 28 that fixes the toner transferred onto the sheet. The transfer unit 26 forms an electrostatic latent image on the photosensitive member by a charging unit and an exposure unit (not shown), and attaches toner to the surface of the photosensitive member by electrostatic force to form a toner image. The toner image formed here is formed based on the document image. The transfer roller on which the toner image is transferred from the photoconductor or the photoconductor is provided on the main conveyance path 14, and the toner is transferred onto the paper as the paper is conveyed here.

  The fixing unit 28 is provided on the main conveyance path 14 downstream from the transfer unit 26. This is a method in which the sheet to which the toner is attached is pressed by a fixing roller while heating, whereby the toner transferred to the sheet is fixed on the sheet.

  The inspection device 16 is roughly divided into a reading device 17, a main sheet 46 that presses the paper against the conveyance guide plate 38, and an inspection control unit (not shown) (see FIGS. 2 and 3). The reading device 17 includes a lamp 40, an imaging lens 42, and a CCD sensor 44, and reads an image printed on a sheet by the printing unit 12. The reading device 17 is provided downstream from the fixing unit 28. However, it is desirable to be close to the fixing unit 28 in order to shorten the overall processing time and to reduce the size of the apparatus. The image read by the reading device 17 is output to the inspection control unit as inspection image data. In this embodiment, a CCD sensor is used as a reading device. However, another device such as a CMOS sensor may be used as long as it reads an image printed on paper.

  The main sheet 46 is a sheet-like member having flexibility, and is provided on the upstream side of the reading device 17. This functions as a pressing unit that presses the transported paper against the transport guide plate 38. The main sheet 46 is hung on the conveyance guide plate 38 from above, and the front end portion thereof is installed immediately before the image reading position R by the reading device 17. The main sheet 46 has substantially the same width as the conveyance guide plate 38. The conveyed paper 50 passes between the main sheet 46 and the conveyance guide plate 38 and reaches the image reading position R. At this time, the sheet is pressed against the conveyance guide plate 38 by the main sheet 46 over its entire width. By this pressing, undulation and curl generated on the paper are corrected, and the paper can be flattened and conveyed to the reading position R.

  The inspection control unit has a function corresponding to a determination unit, and determines whether the print result is acceptable. This pass / fail judgment is made by comparing and collating the inspection image data acquired by the reading device 17 with the document image data stored in advance. Then, the inspection result obtained as a result of the comparison and collation is output to the image printing control unit.

  The paper discharge unit 24 includes a normal paper discharge tray 34 that discharges the paper on which image printing has been completed normally, and an abnormal paper discharge tray 36 that discharges paper that has been determined to have a poor print result.

  A switch provided at the branch point of each transport path determines whether the paper transported along the main transport path 14 is led to the normal paper discharge tray 34, the abnormal paper discharge tray 36, or the double-side transport path 18. (Not shown). This switch is controlled by the image printing control unit.

  Next, the flow of image printing in the printer 10 will be described. When image printing is performed on paper, document image data that is an image to be printed is input to the image printing control unit. The document image data is input, for example, by transmitting document image data from another computer or the like to the image printing control unit via a communication device. The input document image data is stored in the image printing control unit and output to the inspection control unit. The inspection control unit stores the document image data. Of course, original image data may be acquired by reading a sheet on which a predetermined image is printed.

  The image printing control unit develops the toner image on the photosensitive member by controlling the charging device, the exposure device, and the like based on the stored document image data. Further, the transport roller 15 is driven to feed the paper from the predetermined paper feed trays 30 and 32 to the main transport path 14. The fed paper is transported along the main transport path 14, and the toner image is transferred by the transfer unit 26 and the toner is fixed by the fixing unit 28. As a result, image printing based on the document image data is performed on the paper.

  The paper on which the image is printed by the printing unit 12 is further conveyed to the image reading position R, and the image printed on the paper is read by the reading device 17. The inspection control unit compares and collates inspection image data acquired by the reading device 17 with previously stored document data. If the difference amount between the two images is lower than a predetermined threshold value, it is determined that the image has been printed normally. If the difference amount is larger than the predetermined threshold value, it is determined that the printing result is defective.

  Here, the paper conveyed to the reading position may be curled or undulated in advance or in the course of conveyance. In particular, when printing an image, it is pressed against a photoreceptor or a fixing roller and bent into an arc shape. Therefore, the paper is likely to curl. In addition, undulation may occur due to heat generated around the fixing unit.

  If the paper is curled or wavy, the image printed on the surface will appear distorted. For this reason, the inspection image acquired by the reading device 17 is also distorted according to the curl or undulation of the paper. Therefore, even when the image is originally printed normally, if the paper is curled or wavy, the difference between the obtained inspection image data and the original image data becomes large, and it is determined that the printing result is defective. May be. However, the inspection to be performed by the inspection device 16 is whether or not printing has been performed normally, and it is not desirable that what has been normally printed due to curling or waviness of the paper is determined to be a defective printing result.

  Therefore, in the present embodiment, the main sheet 46 is provided on the upstream side of the reading device 17. The conveyed paper 50 passes under the main sheet 46 before reaching the image reading position R by the reading device 17. During this passage, the sheet 50 is pressed against the surface of the conveyance guide plate 38 by the weight of the main sheet 46. Then, the paper 50 coming out from the front end of the main sheet 46 positioned immediately before the image reading position R is corrected to be curled and swelled and flattened.

  Therefore, the reading device 17 can read an image printed on a sheet in a flat state, and can acquire an image of an accurate printing result. This makes it possible to inspect the printing result with higher reliability. In the present embodiment, the leading edge of the main sheet 46 is provided immediately before the image reading position R. For this reason, no curling or undulation occurs after passing through the main sheet 46, and the image can be reliably read in a flat state. Further, the main sheet 46 does not interfere with image reading. Further, the main sheet 46 is made of a sheet-like member having flexibility. Therefore, even if a force is generated in the direction opposite to the conveyance direction during the pressing due to friction or the like, the force in the direction opposite to the conveyance is released by appropriately changing the shape. Therefore, the conveyance of the paper is not hindered.

  The result of the inspection by the inspection device 16 is output to the image printing control unit. The image printing control unit appropriately controls the sheet conveyance path according to the inspection result. That is, when it is determined that the printing result is normal, the paper is transported to the normal paper discharge tray 34 or the double-side transport path 18. If it is determined that the print result is defective, the image is conveyed to the abnormal paper discharge tray 36 and the image is printed again on another sheet.

  As described above, according to the present embodiment, it is possible to inspect a printing result with higher reliability. In the present embodiment, the width of the main sheet 46 is substantially the same as that of the conveyance guide plate 38, but may be smaller as long as the sheet can be flattened. Therefore, for example, the width may be such that only a part of the paper is pressed against. In addition, the configuration is not limited to the above as long as the sheet is pressed against the conveyance guide plate immediately before the image reading position and flattened. For example, instead of the main sheet, a roller that presses almost the entire width of the paper may be used.

  Next, another embodiment will be described with reference to FIG. FIG. 4 is a schematic side view of the periphery of the reading device 17 in a printer according to another embodiment. In the present embodiment, in addition to the main sheet 46, a sub sheet 48 is further provided as a pressing unit that presses the paper 50 against the conveyance guide plate 38.

  The sub sheet 48 is a flexible sheet-like member provided on the downstream side of the image reading position R. The sub sheet 48 is hung on the conveyance guide plate 38 at a position immediately after the image reading position R. Therefore, the conveyed paper 50 passes under the sub-sheet 48 and is pressed onto the conveyance guide plate 38 by the weight of the sub-sheet 48 when passing. Further, the width is substantially the same as that of the conveyance guide plate 38 so that the entire width of the conveyed sheet can be pressed.

  As described above, by providing the sub sheet 48 that presses the sheet against the conveyance guide plate 38 immediately after the image reading position R, the conveyed sheet 50 is pressed immediately before and after the image reading position R. As a result, the sheet 50 can be flattened more reliably, and the printed result can be inspected more accurately.

  Next, another embodiment will be described with reference to FIG. FIG. 5 is a schematic side view of the periphery of the reading device 17 in a printer according to another embodiment. In the present embodiment, a vertical movement mechanism 51 that moves the main sheet 46 up and down is further provided.

  The vertical movement mechanism 51 functions as a pressing force adjusting unit that adjusts the pressing force with which the main sheet 46 presses the paper 50 against the conveyance guide plate 38, and can move the main sheet 46 in the vertical direction. By moving the main sheet 46 up and down, the drooping amount L of the main sheet 46 on the conveyance guide plate 38 can be changed. By adjusting the sagging amount L, it is possible to adjust the pressing force for pressing the paper 50 against the conveyance guide plate 38. That is, when the drooping amount L changes, the contact area between the main sheet 46 and the paper 50 and the deformation amount of the main sheet 46 also change. Since the pressing force changes according to the contact area and the amount of deformation, the pressing force also changes as the sag amount L changes.

  Therefore, when it is desired to increase the pressing force for pressing the sheet against the conveyance guide plate 38 with the main sheet 46, the main sheet 46 is moved downward by the vertical movement mechanism 51 to increase the droop amount L. On the other hand, when it is desired to reduce the pressing force, the main sheet 46 may be moved upward by the vertical movement mechanism 51 to reduce the sagging amount L. That is, by providing the vertical movement mechanism 51 that moves the main sheet 46 up and down, the pressing force for pressing the paper can be adjusted, and the paper can be pressed with a more appropriate pressing force. Therefore, the paper can be more effectively flattened, and the print result can be inspected more reliably.

  The vertical movement mechanism 51 may be any mechanism as long as the main sheet 46 can be moved up and down to adjust the amount L of the main sheet 46 hanging onto the conveyance guide plate 38. For example, the mounting member of the main seat 46 may be moved up and down using a ball screw and a slider, a motor that drives the ball screw, and the like. Further, the main sheet 46 may be automatically moved up and down in accordance with the thickness and nature of the paper (ease of curling and undulation).

  Next, another embodiment will be described with reference to FIG. FIG. 6 is a schematic side view of the periphery of the reading device 17 in a printer according to another embodiment. In the present embodiment, an adjustment sheet 52 and a conveyance direction moving mechanism 54 are provided as pressing force adjusting means for pressing the paper.

  The adjustment sheet 52 is a flexible sheet-like member hung on the main sheet 46. Further, the transport direction moving mechanism 54 moves the adjustment sheet 52 in the forward direction and the reverse direction of the transport, and adjusts the drooping position I of the adjustment sheet 52 on the main sheet 46. By adjusting the sag position I of the adjustment sheet 52 on the main sheet 46, the pressing force with which the main sheet presses the sheet against the conveyance guide plate 38 can be adjusted.

  That is, by adjusting the drooping position I of the adjustment sheet 52, the force with which the adjustment sheet 52 presses the main sheet 46 in the vertical direction can be adjusted. As a result, the main sheet pushes the sheet against the conveyance guide plate 38. The pressing force applied can be adjusted. Accordingly, when it is desired to increase the pressing force for pressing the paper against the main transport path 14 with the main sheet 46, the transport sheet moving mechanism 54 moves the adjustment sheet 52 in the reverse transport direction (left side in FIG. 6). Conversely, when it is desired to reduce the pressing force, the adjustment sheet 52 may be moved in the forward conveyance direction (right side in FIG. 6) by the conveyance direction moving mechanism 54 to reduce the sag amount L.

  Thus, by adjusting the adjustment sheet 52 suspended on the main sheet 46 and the conveyance direction moving mechanism 54 for moving the adjustment sheet 52 in the conveyance direction, the pressing force of the sheet by the main sheet 46 is adjusted. Can do. Therefore, the paper can be leveled more effectively, and the print result can be inspected with higher reliability. Further, since the pressing force is adjusted by moving the adjustment sheet 52, the main sheet 46 does not move even if the pressing force is changed. Accordingly, the sheet can be pressed at an appropriate position, and the main sheet 46 does not hinder image reading.

  As the transport direction moving mechanism, any mechanism may be used as long as the adjustment sheet 52 can be moved in the transport direction and the hanging position I on the main sheet 46 can be adjusted. Further, the configuration is not limited to the above as long as the pressing force can be adjusted without changing the position of the main seat 46. For example, the main sheet 46 may be configured to be pressed from above with a suitable pressing force with a plate material or the like.

1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. FIG. 2 is a schematic side view of the vicinity of a reading device of a printer. FIG. 2 is a schematic top view of the vicinity of the reading device of the printer. It is a schematic side view of the periphery of the reading device of the printer of another embodiment. It is a schematic side view of the periphery of the reading device of the printer of another embodiment. It is a schematic side view of the periphery of the reading device of the printer of another embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Printer, 12 Printing part, 15 Conveyance roller, 16 Inspection apparatus, 17 Reading apparatus, 22 Storage part, 24 Paper discharge part, 26 Transfer part, 28 Fixing part, 38 Conveyance guide plate, 46 Main sheet, 48 Sub sheet, 50 sheets, 51 vertical movement mechanism, 52 adjustment sheet, 54 transport direction movement mechanism, R image reading position, L sag amount, I sag position.

Claims (2)

A printing unit that prints an image on paper based on the document image data;
Inspection means for inspecting the image printing result by the printing unit;
An image forming apparatus having
Inspection means
A reading unit that is provided on a paper conveyance path formed by a conveyance guide plate and that reads an image printed on the paper by a printing unit to obtain inspection image data;
Judging means for judging the quality of the print result based on the inspection image data;
Pressing means for pressing the paper against the conveyance guide plate in the vicinity of the image reading position by the reading means to flatten the paper;
Have
The pressing means is
A main sheet, which is a flexible sheet-like member hung on the conveyance guide plate so that its leading end is immediately before the image reading position, and sandwiches the conveyed paper with the conveyance guide plate When,
An adjustment sheet that is hung on the main sheet and made of a flexible sheet-like member;
A transport direction moving means for adjusting a pressing force to press the paper against the transport guide plate by moving the adjustment sheet in the transport direction and adjusting a dripping position of the adjustment sheet;
An image forming apparatus comprising: A printing result inspection apparatus that is attached to an image forming apparatus that prints an image on paper based on document image data and inspects the result of image printing by the image forming apparatus,
A reading unit that is mounted on a conveyance path of an image forming apparatus formed by a conveyance guide plate and that reads an image printed on a sheet by the image forming apparatus to acquire inspection image data;
Judging means for judging the quality of the print result based on the inspection image data;
Pressing means for pressing the paper against the conveyance guide plate in the vicinity of the image reading position by the reading means to flatten the paper;
Have
The pressing means is
A main sheet, which is a flexible sheet-like member hung on the conveyance guide plate so that its leading end is immediately before the image reading position, and sandwiches the conveyed paper with the conveyance guide plate When,
An adjustment sheet that is hung on the main sheet and made of a flexible sheet-like member;
A transport direction moving means for adjusting a pressing force to press the paper against the transport guide plate by moving the adjustment sheet in the transport direction and adjusting a dripping position of the adjustment sheet;
A printing result inspection apparatus comprising:

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